BEHAVIOUR OF AEROSOLS FORMED BY CLUSTERING OF MOLECULES AROUND GASEOUS IONS

Behaviour of aerosols formed by the clustering of vapour molecules around negative gaseous ions has been studied using thorium-B atoms as tracer. Small negative ions of high mobility are first converted to large negative ions of low mobility by passing these through a flask containing the liquid whose vapour is to be studied, using nitrogen as carrier gas. The large ions so formed consist of clusters of molecules of the vapour. These clusters are found to be stable even after the charge is lost and behave as submicron aerosol. This aerosol, along with vapour and carrier gas, fills a neoprene reservoir. In the reservoir, the aerosol grows in size by coagulation and also probably by the diffusion of vapour molecules to the surface of the particles. Mean residence time of the aerosol particles in the neoprene reservoir at different times of growth is measured by introducing thoron gas in the reservoir and studying the change in activity due to thorium-B with time. The mean aerosol particle size at different times is estimated from the residence time in the reservoir. The aerosols investigated are the products of very early stages of nucleation by ions. The possible role of this mechanism in the formation of natural condensation nuclei is discussed. © 1969.